Plants and environments

• Pollution


  Acid rain can cause soils to become too acidic, killing some plants and inhibiting the growth of others
• Chemicals used


  • Pesticides
  • Fungicides
  • Herbicides
  • Fertilisers
  • Liming
• Chemicals


  • Affect the growth and distribution of plants, and are likely to reduce biodiversity in a natural habitat
• Over-harvesting


  Depletes the soil of nutrients, making it difficult for plants to grow
• Monocultures


  Growing only one type of plant in a particular field, which keeps depleting the soil of the same minerals, which are essential for healthy plant growth
• Habitat


  A place with suitable conditions for a variety of different plants and animals to live in. There are many different types of habitat, e.g. woodland, tropical rainforest, freshwater ponds
• Biodiversity


  The variety of life in a particular habitat. It includes all the plants, animals and microorganisms that live there
• Soil pH


  Most plants grow best in neutral or slightly acidic soil. The pH range of most soils is between 4.5 and 7.5, although there are a few plants that grow better in more extreme conditions, in soils as acidic as pH 3 or as alkaline as pH 9
• Soil aeration


  • Oxygen is needed for plants to respire, for microorganisms to respire, to help plants absorb water and nutrients, to help prevent toxins forming in the soil, and to help prevent plants from contracting diseases
• Transpiration


  Evaporation of water from the surface of the leaves of plants
• Mineral ions


  • Calcium, Ca²+
  • Magnesium, Mg2+
  • Iron, Fe3+
  • Potassium, K
  • Nitrate, NO
  • Phosphate, PO3
  • Sulfate, SO2-
• Calcium deficiency


  • Tissues become soft and the plant is likely to wilt
• Magnesium deficiency


  • Magnesium is an essential part of the chlorophyll molecule. Without chlorophyll, the plant is unable to photosynthesise so cannot grow
• Iron deficiency


  • Leaves become bleached, leading to deficiency in chlorophyll and reduced photosynthesis
• Potassium deficiency


  • Potassium is essential for the formation of healthy flowers and fruit. Leaves lose colour at the tips and may curl and crinkle
• Nitrate deficiency


  • Leaves lose colour at the tips and may curl and crinkle. Plants become short and spindly and deficient in chlorophyll. They may wilt and die
• Phosphate deficiency


  • Plants grow more slowly, leading to dwarfed or stunted plants
• Sulfate deficiency


  • Veins in the leaves take on a reddish colour, leading to a deficiency in chlorophyll. Leaves may also become twisted and brittle
• Low levels of chlorophyll mean

  Chloroplasts can’t take in as much light so Rate of photosynthesis decreases
• The main function of the xylem is to transport water from roots to leaves.
• Phloem transports sugars made by photosynthesis throughout the plant.
• Human effects-trampling

  Can cause uneven distribution of plants
• Habitat destruction

  includes deforestation or clearing of land for development of agriculture
• Acid rain


  • Can cause soils to become too acidic
  • Kills some plants
  • Inhibits the growth of others
• Chemicals used

  • Pesticides
  • Fungicides
  • Herbicides
  • Fertilisers
  • Liming
• Use of chemicals

  • Affect the growth and distribution of plants
  • Likely to reduce biodiversity in a natural habitat
• Over-harvesting

  • Depletes the soil of nutrients
  • Makes it difficult for plants to grow
• Monocultures

  • Involves growing only one type of plant in a particular field
  • Keeps depleting the soil of the same minerals
  • Essential for healthy plant growth
• Soil pH

  Measure of the acidity or alkalinity of soil
• Soil aeration

  The amount of air in the soil
• Plants

  • Sensitive to changes in pH
  • Most grow best in neutral or slightly acid soil
  • pH range of most soils is between 4.5 and 7.5
  • Some grow better in more extreme conditions, in soils as acidic as pH 3 or as alkaline as pH 9
• Higher temperatures

  Respiration takes place more quickly than Photosynthesis
• Respiration taking place more quickly than Photosynthesis

  Plants cannot grow
• Lower temperatures result

  Poor growth as Photosynthesis is slow
• Temperatures fall below freezing point of water (0°C)

  Plant cells and tissues can be destroyed
• Water is important because

  • It dissolves minerals in the soil which can be taken up by the roots to all parts of the plant
  • Moisture in the air is absorbed by the leaves
• Soil becomes waterlogged

  Can cause roots to rot, killing the plant
• Plants lose water from their leaves by transpiration


  This water needs to be replaced
• Aeration of the soil

  • Oxygen is needed for plants to respire
  • Oxygen is needed for microorganisms to respire, as these are needed to decompose organic matter and for nitrification of the soil
  • Oxygen helps plants to absorb water and nutrients
  • Oxygen helps prevent toxins forming in the soil
  • Oxygen helps prevent plants from contracting diseases
• Transect

  A line across a habitat, usually placed using a tape measure